Devices with low melting point alloy for control of device flexibility

ABSTRACT

A continuum device/manipulator includes a first flexible tube, a low melting point (LMP) alloy disposed within the first flexible tube, and a temperature adjustment element that applies heat or cooling to change a phase of the LMP alloy. Changing the phase of the LMP alloy controls a flexibility of the first flexible tube.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.62/153,175 filed on Apr. 27, 2015, the entire contents of which arehereby incorporated herein by reference.

STATEMENT OF GOVERNMENTAL INTEREST

This invention was made with Government support under contract number1R01EB016703-01A1 awarded by the National Institutes of Health (NIH).The Government has certain rights in the invention.

TECHNICAL FIELD

Example embodiments generally relate to continuum devices and, inparticular, relate to devices with a Low Melting Point (LMP) alloy forcontrol of device flexibility.

BACKGROUND

Snake-like devices/manipulators have a wide variety of uses in variousindustrial, medical, and general fields for positioning and/or holdingobjects. However, these devices/manipulators and arms are generallyconstructed to meet one of two objectives, flexibility or strength. Anexample of a continuum device may be a continuum manipulator used in themedical field. Continuum manipulators may generally be constructed of aflexible polymer tube, which may be snaked to the desired locationbending around obstructions. However, the typical continuum manipulatormay have limited strength to maintain a particular position when pushedagainst an object, such as during drilling, cutting, probing, or thelike. Reaction force or other external forces from these operations maycause the typical continuum manipulator to be displaced away from thedesired position. This may be particularly problematic in applicationsrequiring high accuracy, such as medical procedures.

In contrast, devices that are constructed to have high strength may belimited in flexibility. For example, articulated arms generally includea plurality of rigid segments with joints. The rigid segments mayprevent the snaking utilized by more continuum devices.

Typical gripping or grasping manipulators may be complex and may notmorph around an object of interest while preserving the strength of thegrip. For instance, a pinch gripper may be simple and have a relativelyhigh strength, but have very limited dexterity and flexibility. Morecomplex grippers may be significantly more physically andcomputationally complex.

A recent solution utilizes a granular material in a continuum or elasticmembrane. The device may be activated, e.g. become stiff or rigid, byapplying a vacuum to the membrane causing a jamming effect of thegranular material. The device may be when not activated and become rigidwhen activated. However, the device may be limited by vacuum pressure,require a bulky vacuum system, and require vacuum to be appliedcontinuously when activated.

A gripper utilizing the granular material and a vacuum may have a veryhigh dexterity, but as discussed above, the strength is limited by thevacuum, which must be continuously supplied. Further, the gripperutilizing the granular material and vacuum may also require the bulkyvacuum system, which must be again continuously applied when activated.

BRIEF SUMMARY OF SOME EXAMPLES

Accordingly, some example embodiments may enable a continuumdevice/manipulator to be provided including a first flexible tube, a LMPalloy disposed within the first flexible tube, and a temperatureadjustment element configured to apply heat or cooling to change a phaseof the LMP alloy. Changing the phase of the LMP alloy controlsflexibility of the first flexible tube.

In another embodiment, a grasper is provided including a flexiblemembrane, a LMP alloy is disposed within the flexible membrane, and atemperature adjustment element configured to apply heat or cooling tochange the phase of the LMP alloy. Changing the phase of the LMP alloycontrols the flexibility of the flexible membrane.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

Having thus described the continuum device/manipulator in general terms,reference will now be made to the accompanying drawings, which are notnecessarily drawn to scale, and wherein:

FIG. 1 illustrates an example continuum device/manipulator according toan example embodiment.

FIGS. 2A-2C illustrate example configurations of a device with LMP alloyaccording to an example embodiment.

FIG. 3 illustrates an example schematic of a continuumdevice/manipulator according to an example embodiment.

FIG. 4 illustrates an example cross-section of a continuumdevice/manipulator according to an example embodiment.

FIG. 5 illustrates an example continuum device/manipulator withnon-continuum segments according to an example embodiment.

FIG. 6 illustrates an example of a continuum device/manipulator with ondemand binary stiffness according to an example embodiment.

FIG. 7 illustrates a segmented continuum device/manipulator according toan example embodiment.

FIG. 8 illustrates navigation of a segmented continuumdevice/manipulator around an obstacle according to an exampleembodiment.

FIG. 9 illustrates a continuum device/manipulator employed as asteerable cutter according to an example embodiment.

FIG. 10 illustrates a continuum device/manipulator employed as asteerable cutter according to an example embodiment.

FIG. 11 illustrates a segmented continuum device/manipulator employed asa steerable cutter according to an example embodiment.

FIG. 12 illustrates navigation of a continuum device/manipulatoremployed as a steerable cutter around an obstacle according to anexample embodiment.

FIGS. 13 and 14 illustrate example medical applications of a continuumdevice/manipulator according to an example embodiment.

FIG. 15 illustrates a grasper according to an example embodiment.

FIGS. 16A-16C illustrate example positioning systems for a grasperaccording to an example embodiment.

FIG. 17 illustrates a smart structure of a LMP alloy according to anexample embodiment.

FIG. 18 illustrates an example controller for a continuumdevice/manipulator according to an example embodiment.

DETAILED DESCRIPTION

Some example embodiments now will be described more fully hereinafterwith reference to the accompanying drawings, in which some, but not allexample embodiments are shown. Indeed, the examples described andpictured herein should not be construed as being limiting as to thescope, applicability or configuration of the present disclosure. Rather,these example embodiments are provided so that this disclosure willsatisfy applicable legal requirements. Like reference numerals refer tolike elements throughout. As used herein, operable coupling should beunderstood to relate to direct or indirect connection that, in eithercase, enables functional interconnection of components that are operablycoupled to each other.

In an example embodiment, a continuum device/manipulator is providedincluding a LMP alloy which may selectively change phases to control theflexibility of the continuum device/manipulator. A temperatureadjustment element, such as a resistive heater or coolant provided by acoolant pump may cause the change in phase of the LMP alloy by changingthe temperature. The ability to control the flexibility of the continuumdevice/manipulator may allow for the device/manipulator to be positionedwhile flexible. Then changing the phase of the LMP alloy may cause thecontinuum device/manipulator to be rigid at a desired location. Therigidity at the desired location may significantly increase a payloadcapacity of the continuum device/manipulator.

In some example embodiments, the temperature adjustment element mayinclude a plurality of segments that may individually apply heat orcooling to the LMP alloy. A controller may be utilized to control theapplication of heat and cooling allowing for on demand binary stiffnessof each segment of the continuum device/manipulator. Utilizing steeringcables in conjunction with the on demand binary stiffness of thesegments may allow for precise steering of the continuumdevice/manipulator around objects, which may not have been possibleusing typical device/manipulators.

In some example embodiments, a grasper is provided that utilizes the LMPalloy. The LMP alloy may be disposed within an elastic membrane. Thegrasper may engage an object while the LMP alloy is in a liquid phase,which may conform or morph to contours of the object. The LMP alloy maythen change to a solid phase, which may cause a rigid engagement withthe object. Since the grasper conforms to the contours of the objectbefore becoming rigid, the grasper may have a significantly higher gripstrength than typical grippers. Thus the grasper may be capable ofholding heavier objects.

In embodiments of the continuum device/manipulator and/or the grasper, arelatively small power supply may be used to supply power to thetemperature adjustment element, which may also be relatively simple indesign and implementation. Additionally, once the LMP alloy is in solidphase, power is not required to maintain the LMP alloy in the solidphase. As such, the continuum device/manipulator may maintain a desiredshape or grip indefinitely.

Example LMP Alloys

In an example embodiment, a LMP alloy may be utilized to change theflexibility of a continuum device/manipulator or a conforming grasper.The LMP material may be an alloy, such as Field's metal, Wood's metal,or the like; thermoplastic polymers; rheological gel; or the like.Non-toxic alloys, such as Field's metal may be preferable in medicalfields or other fields in which exposure to the LMP alloy is possible orlikely. Field's metal is described in the examples herein to illustratethe principals of the LMP alloy. However, these examples are in no waylimiting. One of ordinary skill in the art would immediately appreciatethat other LMP alloys, such as those described above may be useddepending on the application.

The LMP alloy may have a low melting point, such as 62° C. for Field'smetal. Additionally, the LMP alloy may be a eutectic alloy. For example,Field's metal is a eutectic alloy of bismuth, indium, and tin.Specifically, Field's metal includes the following percentages by weight32.5% Bi, 51% In, and 16.6% Sn. Field's metal may have a high stiffnessin the solid phase and capability to bear high external loads with a lowmelting point.

Example Continuum Device/Manipulator

FIG. 1 illustrates an example continuum device/manipulator 100 accordingto an example embodiment. The continuum device/manipulator 100 mayinclude an LMP alloy to change the flexibility of the continuumdevice/manipulator, as discussed below. The continuum device/manipulator100 may be configured to change flexibility or stiffness on demandallowing for the continuum device/manipulator 100 to be snaked orsteered to a desired position, while the continuum device/manipulator isin a “soft state,” e.g. the LMP alloy is in the liquid phase. Once thecontinuum device/manipulator reaches the desired position, the LMP alloymay change to a solid phase transitioning the continuumdevice/manipulator to a “rigid state.” The eutectic properties of theLMP alloy may allow for a rapid transition between the liquid phase andsolid phase.

In an example embodiment, the continuum device/manipulator 100 mayinclude a tool 101 at the distal end of the continuum device/manipulator100. For example, the tool may include a gripper, a cutter, such ascutting blade, drill bit, or milling blade, a manipulator, or the likeas described below in reference to FIGS. 15 and 16, or the like. Thecontinuum device/manipulator 100 may be scalable for applicationsranging from small intravascular device/manipulators and catheters tolarge industrial drilling operations.

FIGS. 2A-2C illustrate example configurations of a LMP according to anexample embodiment. FIG. 2A depicts a lateral cross-section of acontinuum device/manipulator 100A, including an outer tube 102A, aninner tube 106A, and a LMP alloy 104A. The outer tube 102A and innertube 106A may be a continuum polymer or silicon tube. In this exampleembodiment, the LMP alloy 104A is disposed in a space between the outertube 102A and the inner tube 106A. The inner tube 106A may have an opencenter lumen 108A. The lumen 108A may be configured to pass devices,such as catheters, drills, cameras, or the like; fluids, such aslubricant, coolant, medicines, or the like; control electronics, such aswires or cabling; or the like.

In the example continuum device/manipulator 100B depicted in FIG. 2B,the outer tube 102B may be filled with the LMP alloy 104B. The outertube 102B may be wrapped around the inner tube 106B in a helical spiral.Alternatively, the outer tube 102B may be a helical spiral disposedwithin the inner tube 106B.

In the example continuum device/manipulator 100C depicted in FIG. 2C,the outer tube 102C may be disposed in a lattice pattern around theexterior or interior of inner tube 106C. The lattice structure of outertube 102C may have a common channel at crossing points of the lattice orinclude separate channels. Although three examples of the outer tube102C and LMP alloy 104 configurations are depicted, one of ordinaryskill in the art would immediately appreciate other configurations maybe employed depending on the application, such as interconnected orinterlocking figure eights.

The example continuum device/manipulator 100 depicted in FIG. 2C alsoincludes steering wires 110C or cables. The steering wires 110C may beused to cause the continuum device/manipulator to bend in the softstate. The steering wires 110C may be anchored to anchor points 111C ona collar disposed at the outer surface of the continuumdevice/manipulator 100C and/or the distal end of the continuumdevice/manipulator 100C. Pulling on the steering wires 110C may cause aneccentric point load at the anchored points 111C causing the bending ofthe continuum device/manipulator 100C. Furthermore, shape memory alloys,such as heat activated Nitinol wires, may be used for actuation of thecontinuum device/manipulator.

FIG. 3 illustrates an example schematic of a continuumdevice/manipulator 100D according to an example embodiment. Thecontinuum device/manipulator 100D may include an outer tube 102D, aninner tube 106D, and a PCA 104D disposed between the outer tube 102D andinner tube 106D. The continuum device/manipulator 100 may also include aspring 112D, a power supply 114D, and electrical wires 116. The spring112 may be helical in shape and disposed between the inner tube 106 andouter tube 102. The spring 112 may provide a support structure toprevent kinking of the continuum device/manipulator 100. The spring 112may also provide a mode of force to return the continuumdevice/manipulator to a normal or straight position without exertingenergy on the steering wires, such as steering wires 110C, or servomotors. Additionally, the spring 112D may be configured as a portion ofa temperature adjustment element. The temperature adjustment element, asdiscussed below may include a heating element and/or a cooling elementto apply heat or cooling to the LMP alloy 104D to cause a change inphase of the LMP alloy 104D.

The spring 112 may be configured to be a resistive continuum heater. Thepower supply 114D may supply electrical current to the spring 112D. Theresistance of the spring 112D may cause the spring 112D to increase intemperature and cause the LMP alloy 104D to increase in temperature to alow melting point, for example 62° C. in the case of Field's metal. Inan instance in which the heating of the spring 112D causes the LMP alloy104D to reach or exceed the melting point of the LMP alloy 104D, the LMPalloy 104D may change phase from a solid to a liquid. The continuumdevice/manipulator 100D may be flexible, e.g. soft, in an instance inwhich the LMP alloy 104D is in the liquid phase, and be inflexible, e.g.rigid, in an instance in which the LMP alloy 104 is in the solid phase.

In some example embodiments, the continuum device/manipulator 100D mayinclude a plurality of segments which may be individually controlled,e.g. change phase of the LMP alloy 104D. In an example embodiment, thesegments may be defined by electrical connections at various points ofthe spring 112D. A controller, as discussed below in reference to FIG.18, may be utilized to selectively apply current to the various segmentsof the spring 112D.

For example, in state 0, no portion of the spring 112D is energized andthe entire continuum device/manipulator 100D is rigid. In state I,current is supplied through wire (1) 116D-1 and wire (4) 116D-4, in thiscondition, the entire length of the spring 112D is energized. Energizingthe entire spring 112D may cause the LMP alloy 104D along the entirelength of the continuum device/manipulator 100D to be change to a liquidphase, causing the continuum device/manipulator 100D to be in the softstate. In stage II, current is applied to a lower segment of the spring112D defined by wire (1) 116D-1 and wire (2) 116D-2. The lower portionof the continuum device/manipulator 100D, associated with the lowersegment, transitions to the soft state. An upper segment, which is notenergized, remains in the rigid state. In state III, current is appliedto the segment of the spring 112D defined by the wire (3) 116D-3 andwire (4) 116D-4. The upper portion of the continuum device/manipulator100D, associated with the upper segment, transitions to the soft state.The lower segment, which is not energized, remains in the rigid state.In state IV, a current is applied to a mid segment defined by wire (2)116D-2 and wire (3) 116D-3, which is between the upper segment and thelower segment. The mid segment transitions to the soft state, creating atemporary joint in the continuum device/manipulator 100D. The uppersegment and lower segment, which are not energized, remain in the rigidstate.

In States I, II, III, and IV, portions of the continuumdevice/manipulator 100D in the soft state may be steered by snaking thecontinuum device/manipulator 100D or pulling the steering wires 110D.Once the continuum device/manipulator 100D, or portion of the continuumdevice/manipulator 100D, is in the desired position, the temperatureadjustment element may cause the LMP alloy 104D to change phase to thesolid phase. In an example embodiment, the temperature adjustmentelement may terminate current flow to the continuum device/manipulator100D or segment of the spring 112D. The LMP alloy 104D may coolutilizing ambient heat transfer or may be actively cooled by supplying,via a coolant pump, a coolant to the LMP alloy 104D. The coolant may bewater, lubricant, low temperature gas, or the like. In some exampleembodiments, the coolant may be supplied through a lumen, similar tolumen 108A.

In some embodiments, the adjustable temperature element may additionallyor alternatively include joule heating, resistive wires, Kapton heaters,and/or a hot fluid, which may be passed through the lumen. Furthermore,other heating methods such as induction heating or ultrasound waves canbe used from outside of the device.

In an example embodiment, the stiffness of the LMP alloy 104D may dependon the modulus of elasticity and the moment of inertia of the continuumdevice/manipulator 100D. In the liquid phase, stiffness and modulus ofthe elasticity may be dictated by the stiffness of the spring 112D. Inthe solid phase of the LMP alloy 104D, however, the spring 112D may besurrounded with the LMP alloy 104D as a composite beam behaving as twoparallel springs. In other words, the stiffness of the solid phase LMPalloy 104D may be added to that of the spring 112D. To maintain theshape of the continuum device/manipulator 100D after bending, the addedstiffness of the LMP alloy 104D may overcome elastic energy stored inthe bent spring 112D. The added stiffness of the LMP alloy 104D may alsobe a function of the modulus of elasticity and moment of inertia of theLMP alloy 104D and therefore may be a function of geometry of thecomposite beam geometry. The spring 112D may help to withstand moreexternal load because a stiffness of the spring 112D may be added to thestiffness of the LMP alloy 104D and reinforces the composite beam.

In an example embodiment, the spring 112D, or other temperatureadjustment element, may be surrounded by the LMP alloy 104D, asdiscussed above, and it may be assumed that the generated heat entirelytransfers to the LMP alloy 104D. It may also be assumed that for aspring 112D with a constant pitch, the resistive heating will be uniformalong the length of the spring 112D:

Ri ² t=mcΔθ+mL _(f)

m=ρV

where m is the mass, V is the volume, ρ=9700 kg/m3 is the density, c=172J/kgK is the specific heat capacity, L_(f)=39980 J/kg is the latent heatof LMP alloy 104, Field's metal in the present example, Δθ is thedifference of the room temperature and melting point of Field's metal(62° C.), R is the spring resistance, i is the current, and t is theduration of applying current. Using this equation, a response time ofthe system may be determined based on the generated heat and the amountof Field's metal used.

In some example embodiments, compactness, response time, and energyconsumption of the system are three important design parameters indesigning the spring 112D. From a mechanical aspect, stiffness (k) ofthe spring 112D may be calculated as follows:

k=Gd ⁴/8nD ³

where G is the modulus of the rigidity, d is the wire diameter, D is themean coil diameter, and n is the number of active coils of the spring.

From a thermodynamics aspect, electrical resistance of the spring 112may be defined as:

R=ρL/A

where ρ is the electrical resistivity, R is the electrical resistance, Lis the length, and A is the cross-sectional area of wire.

The above equations may illustrate that increasing the wire diameterincreases the spring stiffness, but decreases the electrical resistance,thereby increasing the time required to change the phase of the LMPalloy 104D.

In an example embodiment, a single-segment continuum device/manipulator100 may be provided. The spring 112D may be a Polytetrafluoroethylene(PTFE) coated stainless steel #304 wire with diameter of 0.635 mm (0.025inch). The PTFE coating thickness may be between 0.004 mm and 0.01 mmand configured to withstand 195° C. The spring 112D may have a 9.8 mmouter diameter, a 1 mm pitch, and a 50 mm length. Measured resistance ofthe spring 112D may be 2.56 ohms. The outer tube 102D and inner tube106D may be continuum silicon rubber tubes (Shore A35). The inner tube106D may have an outer diameter of 9.52 mm and a wall thickness of 1.59mm. The outer tube 102D may have a wall thickness of 3 mm and an innerdiameter of 10 mm. A LMP alloy 104D, of Field's metal (such asmanufactured by RotoMetals, Inc), may be disposed between the inner tube106D and outer tube 106D. The power supply 114D may pass the electriccurrent through the spring 112D generating 30 W with constant voltage of8.5 V and corresponding current of 3.32 A. The average response time formelting the LMP alloy 104D, e.g. the Field's metal, from 45° C. to 62°C. may be about 3.5 seconds.

In another example embodiment, a two-segment continuumdevice/manipulator may be provided. The spring 112 may be a PTFEstainless steel wire with a length of 72 in. The spring 112 may have anouter diameter of 9.8 mm, pitch of 1 mm, and length of 115 mm. The innertube 106 and outer tube 102 may be a super soft silicon rubber. Thediameter of the inner tube 106 may be 8 mm. Resistance of the spring 112may be 5.25 ohms. Two steering wires, similar to steering wires 110C maybe anchored to anchor point, similar to anchor points 111C, of opposingexternal collars attached to the outer surface of the outer tube 102Dfor steering the continuum device/manipulator 100D. The power supply andwires may supply electricity to the spring 112D in a manner similar toFIG. 3 including the configuration of the wires 116D-1, 2, 3, 4 andsegments of the spring 112D. Thereby allowing for the shape andflexibility of each segment to be controlled separately. In thisexample, the temperature adjustment element includes a coolant pump,configured to pass cold water, e.g. 4° C. with a 900 ml/min flow rate,through the lumen. The continuum device/manipulator 10D may also includea controller, as discussed below in reference to FIG. 18, configured toapply current to the wires 116-1,2,3,4 and respective segments of thespring 112D to achieve States), I, II, III, and IV.

In an example embodiment, the melting time of the LMP alloy 104D may bedecreased for a respective power increase. For example, melting time maydecrease from 36.7 seconds to 8.2 seconds for heating from 25° C. to 62°C. and from 19.9 seconds to 3.1 seconds for heating from 45° C. to 62°C., based on a power increase from 26.4 W to 74 W. Similarly, higherpower may decrease a phase changing time of the LMP alloy 104. Forexample, the phase change time may decrease from 15 seconds at 26.4 W(3A) to about 2.5 seconds at 74 W (5 A). Furthermore, at 61° C. thecontinuum device/manipulator 100D may be soft enough to be shaped bypulling the steering wires, while the LMP alloy 104D has not completelytransformed to the liquid phase. Therefore, heating the LMP alloy 104D,e.g. Field's metal up to 61° C. rather than 62° C. may reduce the phasechange time (to about 5.7 seconds for heating from 25° C. and 2 secondsfor heating from 45° C.) while having sufficient flexibility to changethe shape of the continuum device/manipulator 100D.

Similar to heating, as the power increases, the corresponding coolingtime may decreases since the surface temperature may remain lower duringhigh power heating. Cooling water may significantly reduce the coolingtime or natural cooling, e.g. convection, to ambient environment. Forexample, the cooling time with water from 62° C. to 45° C. may be 58seconds and 177 second using natural convection.

In an example embodiment, the continuum device/manipulator 100Dincluding 20 g of LMP alloy 104D, e.g. Field's metal, and having alength of 12 cm, a diameter of 13 mm, and a slenderness ratio of 9 maybe capable of withstanding a 1000 gram force without deformation in therigid state, e.g. 50 times the weight of the LMP alloy 104D.

FIG. 4 illustrates example cross-section of a continuumdevice/manipulator 100E according to an example embodiment. Thecontinuum device/manipulator 100 may include an outer tube 102E, aninner tube 106E, and a LMP alloy 104E. In this example, the LMP alloy104E is Field's metal disposed between the inner tube 106E and the outertube 102E. The continuum device/manipulator 100E may also include aspring 112E and wires 116E-1,2 disposed within the LMP alloy 104E. Thewires 116E-1,2 may be connected to the spring 112E at electricalconnections 117E. In some example embodiments, the continuumdevice/manipulator 100E may be cooled by coolant flow through the lumen108E. Additionally or alternatively, the coolant may flow through acooling tube 113E. The cooling tube 113E may be disposed within the LMPalloy 104E. Embedding the cooling tube 113E in the LMP alloy 104E mayallow for more efficient cooling of the LMP alloy 104E, which may resultin faster phase transition between the liquid phase and the solid phase.In an example embodiment, the cooling tube 113E may, additionally oralternatively, pass hot fluid to heat the LMP alloy 104E.

FIG. 5 illustrates an example continuum device/manipulator 100F withnon-continuum segments 118F according to an example embodiment. Thecontinuum device/manipulator 100F may include one or more non-continuumsegments 118F. For example, an outer tube, similar to outer tube 102A,LMP alloy, similar to LMP alloy 104, and temperature adjustment elementmay be contained within an in continuum material, such as metal, e.g.stainless steel, or rigid plastic, e.g. Polyvinyl chloride (PVC) ormedical grade plastics. The continuum device/manipulator 100F may havejoints 120F at which a gap is present between the non-continuum segments118F. The joints 120F may be selectively transitioned between the softstate and rigid state to position or steer the continuumdevice/manipulator 100.

In some example embodiments, the positioning or steering the continuumdevice/manipulator 100 may be executed utilizing steering wires, similarto steering wires 110C as discussed above in reference to FIGS. 2C and3. Additionally or alternatively, the joints 120F may include actuationmotors 120F or steering motors, e.g. servo motors. In an exampleembodiment, the actuation motors 122F may be disposed within a membraneto prevent the LMP alloy from entering the actuation motors 122F. Theactuation motors 122F may position the joints 120F when the joints 120Fare in the soft state. The joints 120F may then be transitioned to therigid state. Once in the rigid state, the joints 118F may retain theposition without joint locks or motor force. In other words, power maynot be necessary to maintain the position of the rigid joints 118F.

FIG. 6 illustrates an example of a continuum device/manipulator 100Gwith on demand binary stiffness according to an example embodiment. Thedepicted continuum device/manipulator 100G includes five segments, whichmay be transitioned between the soft state and rigid state on demand,such as by a controller, as discussed below in reference to FIG. 18. Thecontinuum device/manipulator 100G changes shape from time a through timef. At time a, the continuum device/manipulator 100G is straight and eachof the five segments is in the rigid state, which is indicated by thedark center section. At time b, the first two segments, indicated by theextension of the longitudinal axis x, have been transitioned to the softstate. The soft state of the segments is indicated by the light centersections. At time c, a force F is applied, such as by the steering wire110C. The force F pulls the top of the continuum device/manipulatorrearward applying a point load to the distal end of the continuumdevice/manipulator 100G. The point load causes the continuumdevice/manipulator 100G to bend upward in the y axis. At time d, theforce F is held and the temperature adjustment element stops applyingheat to a LMP alloy, such as LMP alloy 104C. At time e, the first twosegments have transitioned to the rigid state, due to the cooling of theLMP alloy. Time f illustrates a configuration of the continuumdevice/manipulator 100G in which the last three segments have beenpositioned in the opposite direction, e.g. downward, by a processsimilar to the process described in reference to times a-e.

FIG. 7 illustrates a segmented continuum device/manipulator 100Haccording to an example embodiment. The continuum device/manipulator100H may include three segments and a gripper 124H. The gripper 124H maybe configured to pass through the lumen 108 or be mounted to the distalend of the continuum device/manipulator 100. The continuumdevice/manipulator 100H may include four possible flexation steps, e.g.steps 0, 1, 2, and 3. In step 0, each of the segments may be in therigid state, e.g. not activated (N.A.), in which the LMP material 104,e.g. LMP, is in the solid phase. Each of the segments of the continuumdevice/manipulator 100 may be resistant to movement of flexation in Step0.

In Step 1, the first segment, proximate to the gripper 124H, may be inthe soft state, e.g. activated (A), in which the LMP material is in theliquid state. The first segment may be continuum or steerable to adesired position. The second and third segments may be rigid and resistflexation. In Step 2, the first two segments of the continuumdevice/manipulator 100H may be in the soft state, and the third segmentmay be in the rigid state. The first two segments may be continuum orsteerable and the third segment may resist flexation. At Step 3, each ofthe three segments may be in the soft state and may be continuum orsteerable. The more segments which are in the soft state, the more thecontinuum device/manipulator 100H may be able to flex or turn.

FIG. 8 illustrates navigation of a segmented continuumdevice/manipulator 100J around an obstacle 126J according to an exampleembodiment. In an example embodiment, the continuum device/manipulator100J may have segments transition between the soft and rigid state ondemand to assist in the navigation around the obstacle 126J. Forexample, in Step 1, the continuum device/manipulator 100J may have thesecond segment in soft state and the first and third segment in a rigidstate, allowing the continuum device/manipulator 100 to snake around theobstacle 126J. In step 2, the continuum device/manipulator 100J may havethe first segment in the soft state and the second and third segments inthe rigid state. This configuration, in which only the first segment iscontinuum, allows for the first segment to be steered behind theobstacle 126J, which may not be possible using conventional devices.Additionally or alternatively, depending on the configuration of wires,such as wires 116D-1,2,3,4, the lengths of the segments may belengthened or shortened to achieve different curvatures, by selectingspecific ones of the wires.

In a comparison of a typical continuum endoscope and a continuumdevice/manipulator endoscope according to an example embodiment. Thetypical continuum endoscope may need a significant rigidity to be snakedthrough the media, in this example the colon and lower intestine.Additionally, steering the typical continuum endoscope bends the lengthof the endoscope. The rigidity of the typical continuum endoscope maycause deformation of the media. In the present example, deformation ofthe colon and lower intestine may occur. In contrast, the continuumdevice/manipulator endoscope may be less rigid and more preciselysteered through a media, therefore not causing deformation of the media.Once the continuum device/manipulator endoscope has been steered to thedesired position, the continuum device/manipulator endoscope may betransitioned to the rigid state. In the rigid state, tools may be passedthrough the lumen 108 to perform manipulations with accuracy and safety,even while enduring significant external forces, such as 3 kg.

Similarly, in the case of working within an incision, the typicalcontinuum endoscope may be limited in the angle of approach, for examplegrabbing tissue with an endoscopic grasper. The continuumdevice/manipulator endoscope may be steerable to provide a moredesirable or direct angle of approach.

FIGS. 9 and 10 illustrate a continuum device/manipulator 100K employedas a steerable cutter according to an example embodiment. In an exampleembodiment, the continuum device/manipulator 100K may include a cutter128K, such as a cutting blade, rotating head, drill, edge, millingblade, or file. The cutter 128K may be mounted to the distal end of thecontinuum device/manipulator 100K, as depicted in FIG. 9, or may bepassed through a lumen, similar to lumen 108A, as depicted in FIG. 10.In an example embodiment in which the cutter 128K is mounted to thedistal end of the continuum device/manipulator 100K, the diameter of thecutter 128K may be at least as wide as the outer diameter of the innertube, and may be equal to or greater than the outer diameter of thecontinuum device/manipulator 100K. In an instance in which the cutter128K is passed through the lumen, the cutter 128K may have a diameterless than the inner diameter of the lumen.

The continuum device/manipulator 100K may provide a high accuracyplacement of the cutter 128K due to the on demand phase transition andsteering, as discussed above in FIG. 8. Further, as discussed inreference to FIG. 3, once the continuum device/manipulator 100K is inthe desired position, the continuum device/manipulator 100K may betransitioned to the rigid state and have a high resistance to flexation.The resistance to flexation may allow for a greater cutting force to beapplied without the continuum device/manipulator 100K buckling or movingfrom the desired position. Further, the continuum device/manipulator100K may be resistant to vibration, which may be advantageous duringmilling.

FIG. 11 illustrates the segmented continuum device/manipulator 100Kemployed as a steerable cutter. The continuum device/manipulator 100Kdepicted in FIG. 12 may be substantially similar to the continuumdevice/manipulator 100H depicted in FIG. 7. However, the continuumdevice/manipulator 100K of FIG. 12 is configured with a cutter 128K,instead of the gripper 124H.

FIG. 12 illustrates navigation of the continuum device/manipulator 100Kemployed as a steerable cutter to avoid an obstacle 126K according to anexample embodiment. In an example embodiment, the continuumdevice/manipulator 100K may be snaked through a medium or around anobstacle 126K. As discussed above, the cutter 128 may extend from thedistal end of the continuum device/manipulator 100K while being snakedor steered, or the cutter 128K may be passed through the lumen once thecontinuum device/manipulator 100K is in the desired position. By passingthe cutter 128K through the lumen after positioning the continuumdevice/manipulator 100K, the cutting edge of the cutter 128K may not beexposed providing increased safety to the medium.

FIGS. 13 and 14 illustrate example medical applications of continuumdevice/manipulators according to an example embodiment. In the exampledepicted in FIG. 13, a continuum device/manipulator 100L is equippedwith a cutting blade 128L. The continuum device/manipulator 100L may beused to drill a path to the ball of a hip joint. While drilling therelatively straight hole in the hip bone, the continuumdevice/manipulator 100L may be in the rigid state. Once the continuumdevice/manipulator 100L has reached the ball of the hip joint, the firstsegment of the continuum device/manipulator 100L may be transitioned tothe soft state. In a first example, the first segment may be positionedand transitioned back to a rigid state to hollow out the ball of the hipjoint. In a second example, the first segment may be maintained in thesoft state, and the first segment may be steered in a sweeping motion tohollow the ball of the hip joint. In the instance in which the firstsegment is maintained in the soft state, the remaining segments may bemaintained in the rigid state, such that only the first segment moves inthe steering motion.

In the example depicted in FIG. 14, in order to support a traditionalknee surgery, one or more holes may be drilled, by a hand drill 1400 foraccess. The drill holes may necessarily be straight, not allowing for inprocess correction and the drill is generally removed prior toproceeding to the operation to be performed. One or more traditionalarthroscopic tools may be inserted into the one or more holes to performthe operation.

In contrast, in support of a knee surgery utilizing a continuumdevice/manipulator 100M, it may be possible for the continuumdevice/manipulator 100M to be steered, if necessary, during thedrilling. Once the continuum device/manipulator 100M is in position thecontinuum device/manipulator 100M may be transitioned to the rigid stateand cutter 128K removed and replaced with arthroscopic tools, such asgrabber 124, without removing the continuum device/manipulator 100M.Additionally, the continuum device/manipulator 100M may be steered toadditional positions, without necessarily drilling additional holes.

FIG. 15 illustrates a grasper 400 according to an example embodiment. Inan example embodiment, the grasper 400 may include an elastic orcontinuum membrane 402, such as silicon, latex, or the like. Themembrane 402 may be filled with a LMP alloy 404, which may besubstantially similar to the LMP alloy 104, as discussed above inreference to FIG. 3. The membrane 402 may be operably coupled to anend-effector of a positioning unit, such as a continuumdevice/manipulator 100, a robotic arm, a mobile robot, e.g. wheeled ortrack vehicle, or aerial vehicle.

A temperature adjustment element 410 may be disposed within the LMPalloy 404. The temperature adjustment element 410 may be substantiallysimilar to the temperature adjustment element discussed above in FIG. 3.The temperature adjustment element 410 may be utilized to apply heatand/or cooling to change the phase of the LMP alloy 404, insubstantially the same manner as discussed in FIG. 3.

In an example embodiment, the LMP alloy 404 may be in the liquid stateallowing elasticity or flexibility of the membrane 402. The end effector406 and or positioning unit may cause the membrane 402 to engage anobject 408. The membrane 402 and LMP alloy 404 may conform to thecontours of the object 408. The temperature adjustment element 410 maycause the LMP alloy 404 to transition to the solid phase, while themembrane 402 conforms to the contours of the object 408. The transitionof the LMP alloy 404 to the solid phase may cause a rigid engagement ofthe object by the grasper 400.

Since the membrane 402 of grasper 400 can conform to the contours of theobject, the grasper 400 may have significant grip strength while the LMPalloy 404 is in the solid phase, for example, a 20 g LMP alloy 404grasper 400 may be capable or gripping greater than 2 kg. The solidphase, and therefore grip of the object, may be maintained indefinitelywithout applying power to the grasper 400. Additionally, since the gripof the grasper 400 is based on conformance to counters and not applyingpressure to the object 408, the grasper 400 may be used to graspsensitive materials, including without limitations mines and bombs.

FIGS. 16A-16C illustrate example positioning systems for the grasper 400according to an example embodiment. FIG. 16A depicts a track roboticvehicle 500 including the grasper 400. FIG. 16B depicts a robotic arm502 including the grasper 400. FIG. 16C depicts an aerial vehicle, e.g.drone, including the grasper 400.

FIG. 17 illustrates a smart structure 600 according to an exampleembodiment. In an example embodiment, the LMP alloy 404 may be embeddedinto a smart structure 600. The smart structure 600 may be constructedby three dimensional printing and impregnated with the LMP alloy 404 inthe liquid phase. The smart structure 600 may be silicon, latex, orother continuum or elastic material. The smart structure 600 mayminimize the weight and cost of the grasper 400, while maintaining themaximum rigidity.

Example Controller

An example embodiment of the invention will now be described withreference to FIG. 18. FIG. 18 shows certain elements of a controller,e.g. electronic controller, for dynamically steering a continuumdevice/manipulator 100, controlling a positioning system, and/orapplying heat or cooling to the LMP alloy 104, 404 according to anexample embodiment. The controller of FIG. 18 may be employed, forexample, on a client, a computer, a network access terminal, a personaldigital assistant (PDA), cellular phone, smart phone, a network device,server, proxy, or the like. Alternatively, embodiments may be employedon a combination of devices. Accordingly, some embodiments of thepresent invention may be embodied wholly at a single device or bydevices in a client/server relationship. Furthermore, it should be notedthat the devices or elements described below may not be mandatory andthus some may be omitted in certain embodiments.

Referring now to FIG. 18, an apparatus configured for steering thecontinuum device/manipulator 100 or applying heat or cooling to the LMPalloy 104, 404 is provided. In an example embodiment, the controller mayinclude or otherwise be in communication with processing circuitry 50that is configured to perform data processing, application execution andother processing and management services. In one embodiment, theprocessing circuitry 50 may include a storage device 54 and a processor52 that may be in communication with or otherwise control or be incommunication with a temperature adjustment element 40 and/or a steeringsystem 70. As such, the processing circuitry 50 may be embodied as acircuit chip (e.g., an integrated circuit chip) configured (e.g., withhardware, software or a combination of hardware and software) to performoperations described herein. However, in some embodiments, theprocessing circuitry 50 may be embodied as a portion of a server,computer, laptop, workstation or even one of various mobile computingdevices. In situations where the processing circuitry 50 is embodied asa server or at a remotely located computing device, a user interface maybe disposed at another device (e.g., at a computer terminal or clientdevice) that may be in communication with the processing circuitry 50via a device interface and/or a network).

In an example embodiment, the storage device 54 may include one or morenon-transitory storage or memory devices such as, for example, volatileand/or non-volatile memory that may be either fixed or removable. Thestorage device 54 may be configured to store information, data,applications, instructions or the like for enabling the apparatus tocarry out various functions in accordance with example embodiments ofthe present invention. For example, the storage device 54 could beconfigured to buffer input data for processing by the processor 52.Additionally or alternatively, the storage device 54 could be configuredto store instructions for execution by the processor 52. As yet anotheralternative, the storage device 54 may include one of a plurality ofdatabases that may store a variety of files, contents or data sets.Among the contents of the storage device 54, applications may be storedfor execution by the processor 52 in order to carry out thefunctionality associated with each respective application.

The processor 52 may be embodied in a number of different ways. Forexample, the processor 52 may be embodied as various processing meanssuch as a microprocessor or other processing element, a coprocessor, acontroller or various other computing or processing devices includingintegrated circuits such as, for example, an ASIC (application specificintegrated circuit), an FPGA (field programmable gate array), a hardwareaccelerator, or the like. In an example embodiment, the processor 52 maybe configured to execute instructions stored in the storage device 54 orotherwise accessible to the processor 52. As such, whether configured byhardware or software methods, or by a combination thereof, the processor52 may represent an entity (e.g., physically embodied in circuitry)capable of performing operations according to embodiments of the presentinvention while configured accordingly. Thus, for example, when theprocessor 52 is embodied as an ASIC, FPGA or the like, the processor 52may be specifically configured hardware for conducting the operationsdescribed herein. Alternatively, as another example, when the processor52 is embodied as an executor of software instructions, the instructionsmay specifically configure the processor 52 to perform the operationsdescribed herein.

In an example embodiment, the processor 52 (or the processing circuitry50) may be embodied as, include or otherwise control the controller,which may be any means, such as, a device or circuitry operating inaccordance with software or otherwise embodied in hardware or acombination of hardware and software (e.g., processor 52 operating undersoftware control, the processor 52 embodied as an ASIC or FPGAspecifically configured to perform the operations described herein, or acombination thereof) thereby configuring the device or circuitry toperform the corresponding functions of the temperature adjustmentelement 40 and/or steering system 70, as described below.

In some example embodiments, the temperature adjustment element 40 maybe in wired or wireless communication with the processing circuitry 50.The temperature adjustment element 40 may include a coolant pump 46and/or a resistive heating element 44. The processing circuitry 50 maycause the resistive heating element, such as spring 112D, to apply heatto the LMP alloy 104, 404 to cause the LMP alloy 104, 404 to transitionto the liquid phase. For example, the processing circuitry 50 maycontrol which wires 116D apply current to segments of the spring 112D,as discussed in reference to FIG. 3. The processing circuitry 50 mayalso terminate the application of heat to the LMP alloy 104, 404 causinga transition from the liquid phase to the solid phase.

In some example embodiments, the processing circuitry 50 may cause thecoolant pump 46 to pump cold coolant through the cooling tube 113Eand/or the lumen 108C. The cooling applied by the coolant may reduce thetransition time of the LMP alloy 104, 404 from the liquid phase to thesolid phase. Additionally or alternatively, the coolant pump may beconfigured to apply heat to the LMP alloy 104, 404 by pumping heatedliquid through the cooling tube 113E and/or lumen 108C.

The processing circuitry 50 may be in wired or wireless communicationwith the steering system 70. The steering system 70 may include one ormore actuator motors 72, such as actuator 122F, which may be configuredto position joints, such as joints 120F. The steering system 70 may alsoinclude a steering wire actuator 74. The steering wire actuator 74 maybe configured to apply force to one or more steering wires, such assteering wires 110C, to cause segments of the continuumdevice/manipulator 100, which are in the liquid phase to flex, bend, orbe steered into a desired position.

In some example embodiments, the continuum device/manipulator may befurther configured for additional operations or optional modifications.In this regard, in an example embodiment, the temperature adjustmentelement includes a resistive continuum heater. In some exampleembodiments, the temperature adjustment element includes a helicalspring. In an example embodiment, the continuum device/manipulator alsoincludes a power supply, a plurality of wires electrically connectingthe temperature adjustment element to the power supply and a controllerconfigured to control the temperature of the temperature adjustmentelement by energizing at least a portion of the temperature adjustmentelement. In some example embodiments, the temperature adjustment elementincludes a plurality of segments defined by the electrical connectionsof the plurality of wires and the controller is configured to controlthe temperature of at least two segments of the plurality of segments.In an example embodiment, the apparatus also includes a second continuumtube disposed within the first continuum tube. In some exampleembodiments, the LMP is disposed between the first continuum tube andthe second continuum tube. In an example embodiment, the first continuumtube is helically disposed around the second continuum tube. In someexample embodiments, the first continuum tube includes a latticedisposed around the second continuum tube. In an example embodiment, thetemperature adjustment element includes a coolant pump configured tocause coolant to flow through the second continuum tube or a coolingtube. In some example embodiments, the continuum device/manipulator mayalso include a cutter configured to perform a cutting operation at adistal end of the second continuum tube. In an example embodiment, thecutter is configured to pass through the second continuum tube. In someexample embodiments, the continuum device/manipulator also includes oneor more non-continuum segments. In an example embodiment, the continuumdevice/manipulator also includes at least one motorized joint. In someexample embodiments, the continuum device/manipulator also includes amanipulator disposed at a distal end of the first continuum tube. In anexample embodiment, the manipulator includes a continuum membrane andthe LMP is also disposed within the continuum membrane. The temperatureadjustment element is further configured to apply heat or cooling tochange the phase of the LMP within the continuum membrane and changing aphase of the LMP controls the flexibility of the continuum membrane.

In some example embodiments, the grasper may be further configured foradditional operations or optional modifications. In this regard, in anexample embodiment, the manipulator is configured to cause the continuummembrane to engage an object in an instance in which the LMP is in aliquid phase and then cause the temperature adjustment element to causethe LMP to change to a solid phase. Change to the solid phase causes arigid engagement of the continuum membrane and the object. In an exampleembodiment, the manipulator also includes a positioning systemconfigured to move the continuum membrane to a desired position. In someexample embodiments, the positioning system is a robotic arm, a wheeledvehicle, an aerial vehicle, or a continuum device/manipulator.

Many modifications and other embodiments of the devices set forth hereinwill come to mind to one skilled in the art to which these inventionspertain having the benefit of the teachings presented in the foregoingdescriptions and the associated drawings. Therefore, it is to beunderstood that the measuring devices are not to be limited to thespecific embodiments disclosed and that modifications and otherembodiments are intended to be included within the scope of the appendedclaims. Moreover, although the foregoing descriptions and the associateddrawings describe exemplary embodiments in the context of certainexemplary combinations of elements and/or functions, it should beappreciated that different combinations of elements and/or functions maybe provided by alternative embodiments without departing from the scopeof the appended claims. In this regard, for example, differentcombinations of elements and/or functions than those explicitlydescribed above are also contemplated as may be set forth in some of theappended claims. In cases where advantages, benefits or solutions toproblems are described herein, it should be appreciated that suchadvantages, benefits and/or solutions may be applicable to some exampleembodiments, but not necessarily all example embodiments. Thus, anyadvantages, benefits or solutions described herein should not be thoughtof as being critical, required or essential to all embodiments or tothat which is claimed herein. Although specific terms are employedherein, they are used in a generic and descriptive sense only and notfor purposes of limitation.

What is claimed is:
 1. A continuum device/manipulator comprising: afirst flexible tube; a low melting point (LMP) alloy disposed within thefirst flexible tube; and a temperature adjustment element configured toapply heat or cooling to change a phase of the LMP alloy, whereinchanging the phase of the LMP alloy controls a flexibility of the firstflexible tube.
 2. The continuum device/manipulator of claim 1, whereinthe temperature adjustment element comprises a resistive flexibleheater.
 3. The continuum device/manipulator of claim 2, wherein thetemperature adjustment element comprises a helical spring.
 4. Thecontinuum device/manipulator of claim 2, further comprising: a powersupply; a plurality of wires electrically connecting the temperatureadjustment element to the power supply; and a controller configured tocontrol a temperature of the temperature adjustment element byenergizing at least a portion of the temperature adjustment element. 5.The continuum device/manipulator of claim 4, wherein the temperatureadjustment element comprises a plurality of segments defined byelectrical connections of the plurality of wires, and wherein thecontroller is configured to control a temperature of at least twosegments of the plurality of segments.
 6. The continuumdevice/manipulator of claim 1 further comprising: a second flexible tubedisposed within the first flexible tube.
 7. The continuumdevice/manipulator of claim 6, wherein the LMP alloy is disposed betweenthe first flexible tube and the second flexible tube.
 8. The continuumdevice/manipulator of claim 6, wherein the first flexible tube ishelically disposed around the second flexible tube.
 9. The continuumdevice/manipulator of claim 6, wherein the first flexible tube comprisesa lattice disposed around the second flexible tube.
 10. The continuumdevice/manipulator of claim 6, wherein the temperature adjustmentelement comprises a coolant pump configured to cause coolant to flowthrough the second flexible tube or through a cooling tube.
 11. Thecontinuum device/manipulator of claim 6 further comprising: a cutterconfigured to perform a cutting operation at a distal end of the secondflexible tube.
 12. The continuum device/manipulator of claim 11, whereinthe cutter is configured to pass through the second flexible tube. 13.The continuum device/manipulator of claim 6 further comprising: one ormore non-continuum segments.
 14. The continuum device/manipulator ofclaim 1 further comprising: at least one motorized joint.
 15. Thecontinuum device/manipulator of claim 1 further comprising: a grasperdisposed at a distal end of the first flexible tube.
 16. The continuumdevice/manipulator of claim 15, wherein the grasper comprises: aflexible membrane; wherein the LMP alloy is also disposed within theflexible membrane, wherein the temperature adjustment element is furtherconfigured to apply heat or cooling to change the phase of the LMP alloywithin the flexible membrane, and wherein changing a phase of the LMPalloy controls the flexibility of the flexible membrane.
 17. A graspercomprising: a flexible membrane; a low melting point (LMP) alloydisposed within the flexible membrane; and a temperature adjustmentelement configured to apply heat or cooling to change a phase of the LMPalloy, wherein changing the phase of the LMP alloy controls theflexibility of the flexible membrane.
 18. The grasper of claim 17,wherein the grasper is configured to cause the flexible membrane toengage an object in an instance in which the LMP alloy is in a liquidphase and then cause the temperature adjustment element to cause the LMPalloy to change to a solid phase, wherein the change to the solid phasecauses a rigid engagement of the flexible membrane and the object. 19.The grasper of claim 17 further comprising a positioning systemconfigured to move the grasper to a desired position.
 20. The grasper ofclaim 19, wherein the positioning system is one of a robotic arm, awheeled vehicle, an aerial vehicle, and a continuum device/manipulator.